FIG. 1A shows a conventional shielding device 10, which is soldered to a printed circuit (PC) board 15 to protect electronic circuits on the PC board 15 against electromagnetic interference (EMI), lest the electronic circuits should interfere with communication and human health. The shielding device 10 includes an upper lid 11 and a frame 12. The frame 12 has a connector 13 connected thereto for signal input and output. The frame 12 is provided at a predetermined position with a hole for engaging with an end portion of the connector 13, and the area of the connector 13 around the joint of the frame 12 and the connector 13 is riveted and compressed to ensure a firm connection between the two parts. However, the connection of the connector 13 to the frame 12 in the above-described manner will produce a clearance 14 between them, as shown in FIG. 1B. The clearance 14 very possibly forms a path via which electromagnetic wave enters into or leaks out of the shielding device 10. While the leakage of electromagnetic wave can be avoided by manually welding to seal the clearance 14, the welding will cause deformation of the frame 12 and requires additional time and labor costs.